Evaporative emissions detection method with vehicle self leveling suspension compensation

ABSTRACT

Methods and systems are provided for conducting an evaporative emissions test on a fuel system and an emissions control system in a vehicle. In one example, in response to an indication that a vehicle parking condition may result in the isolation of the fuel system from the emissions control system via the unintentional closing of fuel tank valves, a vehicle&#39;s active suspension system may be employed in order to level the vehicle a determined amount such that the fuel system isolation issues may be mitigated prior to an evaporative emissions test procedure. In this way, the entire fuel system and emissions control system may be diagnosed for potential undesired emissions, and potential violations of regulatory requirements for evaporative emissions testing may be reduced.

FIELD

The present description relates generally to methods and systems forcontrolling a vehicle to level a fuel tank prior to conducting anevaporative emissions test.

BACKGROUND/SUMMARY

Vehicle emission control systems may be configured to store fuel vaporsfrom fuel tank refueling and diurnal engine operations, and then purgethe stored vapors during a subsequent engine operation. In an effort tomeet stringent federal emissions regulations, emission control systemsmay be intermittently diagnosed for the presence of undesired emissionsthat could release fuel vapors to the atmosphere. Undesired evaporativeemissions may be identified using engine-off natural vacuum (EONV)during conditions when a vehicle engine is not operating. In particular,a fuel system and/or an emissions control system may be isolated at anengine-off event. The pressure in such a fuel system and/or an emissionscontrol system will increase if the tank is heated further (e.g., fromhot exhaust or a hot parking surface) as liquid fuel vaporizes. As afuel tank cools down, a vacuum is generated therein as fuel vaporscondense to liquid fuel. Vacuum generation is monitored and undesiredemissions identified based on expected vacuum development or expectedrates of vacuum development. However, the entry conditions andthresholds for a typical EONV test may be based on an inferred totalamount of heat rejected into the fuel tank during the prior drive cycle.The inferred amount of heat may be based on engine run-time, integratedmass air flow, miles driven, etc. If these conditions are not met, theentry into the evaporative emissions test is aborted. Thus, hybridelectric vehicles, including plug-in hybrid electric vehicles (HEV's orPHEV's), pose a problem for effectively controlling evaporativeemissions. For example, primary power in a hybrid vehicle may beprovided by the electric motor, resulting in an operating profile inwhich the engine is run only for short periods. As such, adequate heatrejection to the fuel tank may not be available for EONV diagnostics.

An alternative to relying on inferred sufficient heat rejection forentry into an EONV diagnostic test is to instead actively pressurize orevacuate the fuel system and/or emissions control system via an externalsource. For example, a method may perform a pressure-based evaporativeemissions test using a pump to pressurize and/or evacuate the fuelsystem and/or emissions control system. The fuel system and/orevaporative emissions control system may then be monitored for aselected time period, and if the pressure falls below a threshold valueif initially pressurized, or rises above a threshold value if initiallyevacuated, the system identifies undesired emissions. As such, byconducting evaporative emissions tests via the use of an externalpressure source, reliance on heat rejected from the engine may becircumvented.

Whether relying on EONV or actively pressurizing or evacuating the fuelsystem and evaporative emissions control system, the entire fuel systemand evaporative emissions control system must be diagnosed for potentialundesired emissions. This includes the cap or capless area and theentire vapor space of the fuel tank. However, certain parking conditionsmay prevent the testing of the entire fuel system and/or evaporativeemissions control system for undesired emissions. For example, whenparking on steep slopes, liquid fuel can shut closed certain passivefuel tank valves thus restricting communication between the fuel tankand the rest of the evaporative emissions control system. Otherpotential problems resulting from parking on grades may include theformation of an isolated vapor dome space that is not in communicationwith the rest of the fuel system and evaporative emissions controlsystem. For example, due to packaging constraints, fuel tank geometriesmay have many cavities wherein some areas may be higher than others,such that when parking on an incline isolated vapor dome spaces mayresult. Any areas of the fuel system and/or evaporative emissionscontrol system that go unchecked as a result of parking on an inclineviolates regulatory requirements for evaporative emissions testing.

The fact that liquid fuel may result in isolated vapor spaces and arestriction of communication between the fuel tank and the rest of thefuel system and evaporative emissions control system when the vehicle isinclined has been described. For example, US Patent No. US 20140069394teaches conducting an engine-on evaporative emissions test, andresponsive to an unintended closing of a fuel tank vent valve, forexample due to vehicle travel along an incline that is higher than athreshold grade, discontinuing the evaporative emissions test andresuming the test at a later time. However, the inventors herein haverecognized potential issues with such a method. For example, the methoddoes not teach mitigating action for an engine-off evaporative emissionstest where communication between the fuel tank and the rest of the fuelsystem and evaporative emissions control system is restricted and/or oneor more isolated vapor dome space(s) is created due to the vehicle beingparked on a steep slope.

Thus, the inventors herein have developed systems and methods to atleast partially address the above issues. In one example, a method isprovided comprising, responsive to a first vehicle-off condition,maintaining a vehicle compound angle with respect to ground andconducting an evaporative emissions test, and responsive to a secondvehicle-off condition, leveling the vehicle a determined amount and thenconducting the evaporative emissions test.

As one example, responsive to the vehicle-off condition, a fuel leveland a vehicle compound angle are indicated, wherein indicating thevehicle compound includes indicating a vehicle pitch angle and a vehiclebank (roll) angle. Based on the fuel level and vehicle compound angle,it may be determined whether the fuel level and vehicle compound angleis above a predetermined threshold, thus resulting in fuel in the fueltank causing the closing of one or more fuel tank vent valves, and/orcausing the formation of an isolated fuel tank vapor dome(s) resultingfrom one or more section(s) of the fuel tank being isolated from anyother section(s) of the fuel tank. In other words, it may be determinedwhether the fuel level and vehicle compound angle is causing fuel systemisolation issues that may impact the results of an evaporative emissionstest. Determining whether the combined fuel level and vehicle parkingcondition is above a predetermined threshold may be based on computeraided design modeling of the fuel tank. As such, in the first condition,it may be determined that the fuel level and vehicle compound angle isbelow a threshold, thus an evaporative emissions test procedure may beconducted without prior leveling of the vehicle. Alternatively, in thesecond condition, it may be determined that the fuel level and vehiclecompound angle is above a threshold, thus the vehicle may be leveledprior to conducting the evaporative emissions test procedure.

The above advantages and other advantages, and features of the presentdescription will be readily apparent from the following DetailedDescription when taken alone or in connection with the accompanyingdrawings.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an example vehicle propulsion system.

FIG. 2 schematically shows an example vehicle system with a fuel systemand an evaporative emissions system.

FIG. 3A schematically illustrates a vehicle on an indicated grade, anddepicts on-board vehicle sensors configured to detect such an indicatedgrade.

FIG. 3B schematically shows a fuel tank of a vehicle on the gradeindicated in FIG. 3A.

FIG. 3C schematically illustrates a vehicle on an indicated grade,wherein the vehicle has been leveled a determined amount based onon-board vehicle sensors and fuel tank fuel level.

FIG. 3D schematically shows a fuel tank of a vehicle on the gradeindicated in FIG. 3C, subsequent to the vehicle being leveled adetermined amount.

FIG. 4 shows an example method for leveling a vehicle a determinedamount prior to conducting an evaporative emissions test procedure.

FIG. 5 shows a timeline for an example vehicle leveling procedure priorto conducting an evaporative emissions test procedure.

DETAILED DESCRIPTION

The following detailed description relates to systems and methods forperforming an evaporative emissions test on a fuel system and emissionscontrol system. Specifically, the description relates to indicatingwhether a vehicle parking condition may result in the isolation of afuel system from an emission control system via the unintentionalshutting of fuel tank valves, and/or the formation of isolated vapordome(s) within the fuel tank. The vehicle parking condition may includeconditions such as a vehicle is parked on a steep hill, and may befurther based on the level of fuel in the fuel tank under the indicatedvehicle parking condition. Responsive to an indication that a vehicleparking condition may result in the isolation of the fuel system fromthe emission control system and/or the formation of isolated fuel tankvapor dome(s), the vehicle may be leveled a determined amount by thevehicle's active suspension system, such that the fuel system isolationmay be mitigated prior to conducting an evaporative emissions testprocedure. As such, areas of the fuel system that may otherwise gounchecked as a result of certain vehicle parking conditions, may insteadbe checked thus enabling regulatory requirements for evaporativeemissions testing to be met. The systems and methods described hereinmay be applied to a vehicle system comprising an active suspensionsystem, such as the vehicle system depicted in FIG. 1. In one example,the evaporative emissions test procedure may be conducted on a fuelsystem and an emissions control system, where the fuel system is coupledto the emissions control, an engine, and an exhaust system as depictedin FIG. 2. A vehicle parked on a grade may be indicated by on-boardsensors, wherein a vehicle compound angle may be calculated, as depictedin FIG. 3A. Further, a vehicle parked on a grade may unintentionallyclose fuel tank vent valves, depending on the fuel level in the tank andthe vehicle compound angle, as illustrated in FIG. 3B. Based on thelevel of fuel in the tank and the vehicle compound angle as indicated byon-board sensors, a corrective leveling amount of the vehicle may bedetermined, and the vehicle may be leveled a determined amount by thevehicle's active suspension system, as depicted in FIG. 3C. By levelingthe vehicle a determined amount, fuel system isolation and the formationof isolated fuel tank vapor dome(s) may be mitigated, as illustrated inFIG. 3D. A method for detecting and mitigating potential fuel systemisolation and or the formation of isolated fuel tank vapor dome(s) byactively leveling the vehicle using the vehicle's active suspensionsystem is depicted in FIG. 4. A timeline for actively leveling a vehicleprior to conducting an evaporative emissions test procedure using themethod of FIG. 4 is shown in FIG. 5.

FIG. 1 illustrates an example vehicle propulsion system 100. Vehiclepropulsion system 100 includes a fuel burning engine 110 and a motor120. As a non-limiting example, engine 110 comprises an internalcombustion engine and motor 120 comprises an electric motor. Motor 120may be configured to utilize or consume a different energy source thanengine 110. For example, engine 110 may consume a liquid fuel (e.g.,gasoline) to produce an engine output while motor 120 may consumeelectrical energy to produce a motor output. As such, a vehicle withpropulsion system 100 may be referred to as a hybrid electric vehicle(HEV).

Vehicle propulsion system 100 may utilize a variety of differentoperational modes depending on operating conditions encountered by thevehicle propulsion system. Some of these modes may enable engine 110 tobe maintained in an off state (e.g., set to a deactivated state) wherecombustion of fuel at the engine is discontinued. For example, underselect operating conditions, motor 120 may propel the vehicle via drivewheel 130 as indicated by arrow 122 while engine 110 is deactivated.

During other operating conditions, engine 110 may be set to adeactivated state (as described above) while motor 120 may be operatedto charge energy storage device 150. For example, motor 120 may receivewheel torque from drive wheel 130 as indicated by arrow 122 where themotor may convert the kinetic energy of the vehicle to electrical energyfor storage at energy storage device 150 as indicated by arrow 124. Thisoperation may be referred to as regenerative braking of the vehicle.Thus, motor 120 can provide a generator function in some embodiments.However, in other embodiments, generator 160 may instead receive wheeltorque from drive wheel 130, where the generator may convert the kineticenergy of the vehicle to electrical energy for storage at energy storagedevice 150 as indicated by arrow 162.

During still other operating conditions, engine 110 may be operated bycombusting fuel received from fuel system 140 as indicated by arrow 142.For example, engine 110 may be operated to propel the vehicle via drivewheel 130 as indicated by arrow 112 while motor 120 is deactivated.During other operating conditions, both engine 110 and motor 120 mayeach be operated to propel the vehicle via drive wheel 130 as indicatedby arrows 112 and 122, respectively. A configuration where both theengine and the motor may selectively propel the vehicle may be referredto as a parallel type vehicle propulsion system. Note that in someembodiments, motor 120 may propel the vehicle via a first set of drivewheels and engine 110 may propel the vehicle via a second set of drivewheels.

In other embodiments, vehicle propulsion system 100 may be configured asa series type vehicle propulsion system, whereby the engine does notdirectly propel the drive wheels. Rather, engine 110 may be operated topower motor 120, which may in turn propel the vehicle via drive wheel130 as indicated by arrow 122. For example, during select operatingconditions, engine 110 may drive generator 160 as indicated by arrow116, which may in turn supply electrical energy to one or more of motor120 as indicated by arrow 114 or energy storage device 150 as indicatedby arrow 162. As another example, engine 110 may be operated to drivemotor 120 which may in turn provide a generator function to convert theengine output to electrical energy, where the electrical energy may bestored at energy storage device 150 for later use by the motor.

Fuel system 140 may include one or more fuel storage tanks 144 forstoring fuel on-board the vehicle. For example, fuel tank 144 may storeone or more liquid fuels, including but not limited to: gasoline,diesel, and alcohol fuels. In some examples, the fuel may be storedon-board the vehicle as a blend of two or more different fuels. Forexample, fuel tank 144 may be configured to store a blend of gasolineand ethanol (e.g., E10, E85, etc.) or a blend of gasoline and methanol(e.g., M10, M85, etc.), whereby these fuels or fuel blends may bedelivered to engine 110 as indicated by arrow 142. Still other suitablefuels or fuel blends may be supplied to engine 110, where they may becombusted at the engine to produce an engine output. The engine outputmay be utilized to propel the vehicle as indicated by arrow 112 or torecharge energy storage device 150 via motor 120 or generator 160.

In some embodiments, energy storage device 150 may be configured tostore electrical energy that may be supplied to other electrical loadsresiding on-board the vehicle (other than the motor), including cabinheating and air conditioning, engine starting, headlights, cabin audioand video systems, etc. As a non-limiting example, energy storage device150 may include one or more batteries and/or capacitors.

Control system 190 may communicate with one or more of engine 110, motor120, fuel system 140, energy storage device 150, and generator 160.Control system 190 may receive sensory feedback information from one ormore of engine 110, motor 120, fuel system 140, energy storage device150, and generator 160. Further, control system 190 may send controlsignals to one or more of engine 110, motor 120, fuel system 140, energystorage device 150, and generator 160 responsive to this sensoryfeedback. Control system 190 may receive an indication of an operatorrequested output of the vehicle propulsion system from a vehicleoperator 102. For example, control system 190 may receive sensoryfeedback from pedal position sensor 194 which communicates with pedal192. Pedal 192 may refer schematically to a brake pedal and/or anaccelerator pedal.

Energy storage device 150 may periodically receive electrical energyfrom a power source 180 residing external to the vehicle (e.g., not partof the vehicle) as indicated by arrow 184. As a non-limiting example,vehicle propulsion system 100 may be configured as a plug-in hybridelectric vehicle (HEV), whereby electrical energy may be supplied toenergy storage device 150 from power source 180 via an electrical energytransmission cable 182. During a recharging operation of energy storagedevice 150 from power source 180, electrical transmission cable 182 mayelectrically couple energy storage device 150 and power source 180.While the vehicle propulsion system is operated to propel the vehicle,electrical transmission cable 182 may disconnected between power source180 and energy storage device 150. Control system 190 may identifyand/or control the amount of electrical energy stored at the energystorage device, which may be referred to as the state of charge (SOC).

In other embodiments, electrical transmission cable 182 may be omitted,where electrical energy may be received wirelessly at energy storagedevice 150 from power source 180. For example, energy storage device 150may receive electrical energy from power source 180 via one or more ofelectromagnetic induction, radio waves, and electromagnetic resonance.As such, it should be appreciated that any suitable approach may be usedfor recharging energy storage device 150 from a power source that doesnot comprise part of the vehicle. In this way, motor 120 may propel thevehicle by utilizing an energy source other than the fuel utilized byengine 110.

Fuel system 140 may periodically receive fuel from a fuel sourceresiding external to the vehicle. As a non-limiting example, vehiclepropulsion system 100 may be refueled by receiving fuel via a fueldispensing device 170 as indicated by arrow 172. In some embodiments,fuel tank 144 may be configured to store the fuel received from fueldispensing device 170 until it is supplied to engine 110 for combustion.In some embodiments, control system 190 may receive an indication of thelevel of fuel stored at fuel tank 144 via a fuel level sensor. The levelof fuel stored at fuel tank 144 (e.g., as identified by the fuel levelsensor) may be communicated to the vehicle operator, for example, via afuel gauge or indication in a vehicle instrument panel 196. The vehicleinstrument panel 196 may include indicator light(s) and/or a text-baseddisplay in which messages are displayed to an operator. The vehicleinstrument panel 196 may also include various input portions forreceiving an operator input, such as buttons, touch screens, voiceinput/recognition, etc. For example, the vehicle instrument panel 196may include a refueling button 197 which may be manually actuated orpressed by a vehicle operator to initiate refueling. For example, inresponse to the vehicle operator actuating refueling button 197, a fueltank in the vehicle may be depressurized so that refueling may beperformed.

The vehicle propulsion system 100 may also include an ambienttemperature/humidity sensor 198, and sensors dedicated to indicating theoccupancy-state of the vehicle, for example seat load cells 103, doorsensing technology 104, and onboard cameras 105. Vehicle propulsionsystem 100 may also include inertial sensors 199. Inertial sensors 199may comprise one or more of the following: longitudinal, latitudinal,vertical, yaw, roll, and pitch sensors. As one example, inertial sensors199 may couple to a vehicle's restraint control module (RCM) 191, theRCM 191 comprising a subsystem of control system 190. The control systemmay adjust engine output and/or the wheel brakes to increase vehiclestability in response to sensor(s) 199. In another example, the controlsystem may adjust an active suspension system 111 responsive to inputfrom inertial sensors 199. More specifically, active suspension system111 may be connected to any variety of sensors, devices, components,modules, and other input sources located throughout the vehicle. Thesemay include but are not limited to inertial sensors 199, suspensioncontrol modules 193, restraint control modules 192, cruise controlmodules, brake modules, fuel management systems, vision systems,navigation systems, telematics units, as well as any other suitableinput source that can provide pertinent information to active suspensionsystem 111. It should be appreciated that the various input sources canbe embodied in software or hardware, they can be stand-alone devices orthey can be integrated into other devices such as vehicle electronicmodules, and they can be directly connected to active suspension system111 or they can be connected via a communications bus or the like, tocite a few possibilities.

Furthermore, active suspension system 111 may comprise an activesuspension system having hydraulic, electrical, and/or mechanicaldevices, as well as active suspension systems that control the vehicleheight on an individual corner basis (e.g., four corner independentlycontrolled vehicle heights), on an axle-by-axle basis (e.g., front axleand rear axle vehicle heights), or a single vehicle height for theentire vehicle. Active suspension system iii may be used with tractortrailers, commercial and non-commercial trucks, recreational vehicles(RVs), sports utility vehicles (SUVs), cross-over vehicles, passengercars, as well as any other motorized vehicle.

As will be described in further detail below, in one example, activesuspension system 111 may be employed in order to level a vehicle adetermined amount responsive to the vehicle being parked at such anangle that fuel in the fuel tank results in a closing of fuel tankvalves (FIG. 2) and/or results in one or more section(s) of the fueltank being isolated from any other section of the fuel tank (e.g.results in the formation of isolated vapor dome(s)).

FIG. 2 shows a schematic depiction of a vehicle system 206. The vehiclesystem 206 includes an engine system 208 coupled to an emissions controlsystem 251 and a fuel system 218. Emission control system 251 includes afuel vapor container or canister 222 which may be used to capture andstore fuel vapors. In some examples, vehicle system 206 may be a hybridelectric vehicle system.

The engine system 208 may include an engine 210 having a plurality ofcylinders 230. The engine 210 includes an engine intake 223 and anengine exhaust 225. The engine intake 223 includes a throttle 262fluidly coupled to the engine intake manifold 244 via an intake passage242. The engine exhaust 225 includes an exhaust manifold 248 leading toan exhaust passage 235 that routes exhaust gas to the atmosphere. Theengine exhaust 225 may include one or more exhaust catalyst 270, whichmay be mounted in a close-coupled position in the exhaust. Exhaustcatalyst may include a temperature sensor 279. In some examples one ormore emission control devices may include a three-way catalyst, lean NOxtrap, diesel particulate filter, oxidation catalyst, etc. It will beappreciated that other components may be included in the engine such asa variety of valves and sensors.

An air intake system hydrocarbon trap (AIS HC) 224 may be placed in theintake manifold of engine 210 to adsorb fuel vapors emanating fromunburned fuel in the intake manifold, puddled fuel from leaky injectorsand/or fuel vapors in crankcase ventilation emissions during engine-offperiods. The AIS HC may include a stack of consecutively layeredpolymeric sheets impregnated with HC vapor adsorption/desorptionmaterial. Alternately, the adsorption/desorption material may be filledin the area between the layers of polymeric sheets. Theadsorption/desorption material may include one or more of carbon,activated carbon, zeolites, or any other HC adsorbing/desorbingmaterials. When the engine is operational causing an intake manifoldvacuum and a resulting airflow across the AIS HC, the trapped vapors arepassively desorbed from the AIS HC and combusted in the engine. Thus,during engine operation, intake fuel vapors are stored and desorbed fromAIS HC 224. In addition, fuel vapors stored during an engine shutdowncan also be desorbed from the AIS HC during engine operation. In thisway, AIS HC 224 may be continually loaded and purged, and the trap mayreduce evaporative emissions from the intake passage even when engine210 is shut down.

Fuel system 218 may include a fuel tank 220 coupled to a fuel pumpsystem 221. The fuel pump system 221 may include one or more pumps forpressurizing fuel delivered to the injectors of engine 210, such as theexample injector 266 shown. While only a single injector 266 is shown,additional injectors are provided for each cylinder. It will beappreciated that fuel system 218 may be a return-less fuel system, areturn fuel system, or various other types of fuel system. Fuel tank 220may hold a plurality of fuel blends, including fuel with a range ofalcohol concentrations, such as various gasoline-ethanol blends,including E10, E85, gasoline, etc., and combinations thereof. A fuellevel sensor 234 located in fuel tank 220 may provide an indication ofthe fuel level (“Fuel Level Input”) to controller 212. As depicted, fuellevel sensor 234 may comprise a float connected to a variable resistor.Alternatively, other types of fuel level sensors may be used.

Vapors generated in fuel system 218 may be routed to an evaporativeemissions control system 251 which includes a fuel vapor canister 222via vapor recovery line 231, before being purged to the engine intake223. Vapor recovery line 231 may be coupled to fuel tank 220 via one ormore conduits and may include one or more valves for isolating the fueltank during certain conditions. For example, vapor recovery line 231 maybe coupled to fuel tank 220 via one or more or a combination of conduits273 and 275.

Further, in some examples, one or more fuel tank vent valves in conduits273 and/or 275. Among other functions, fuel tank vent valves may allow afuel vapor canister of the emissions control system to be maintained ata low pressure or vacuum without increasing the fuel evaporation ratefrom the tank (which would otherwise occur if the fuel tank pressurewere lowered). For example, conduit 273 may include a fill limit ventingvalve (FLVV) 285, and conduit 275 may include a grade vent valve (GVV)283. Further, in some examples, recovery line 231 may be coupled to afuel filler system 219. In some examples, fuel filler system may includea fuel cap 205 for sealing off the fuel filler system from theatmosphere. Refueling system 219 is coupled to fuel tank 220 via a fuelfiller pipe or neck 211.

Further, refueling system 219 may include refueling lock 245. In someembodiments, refueling lock 245 may be a fuel cap locking mechanism. Thefuel cap locking mechanism may be configured to automatically lock thefuel cap in a closed position so that the fuel cap cannot be opened. Forexample, the fuel cap 205 may remain locked via refueling lock 245 whilepressure or vacuum in the fuel tank is greater than a threshold. Inresponse to a refuel request, e.g., a vehicle operator initiatedrequest, the fuel tank may be depressurized and the fuel cap unlockedafter the pressure or vacuum in the fuel tank falls below a threshold. Afuel cap locking mechanism may be a latch or clutch, which, whenengaged, prevents the removal of the fuel cap. The latch or clutch maybe electrically locked, for example, by a solenoid, or may bemechanically locked, for example, by a pressure diaphragm.

In some embodiments, refueling lock 245 may be a filler pipe valvelocated at a mouth of fuel filler pipe 211. In such embodiments,refueling lock 245 may not prevent the removal of fuel cap 205. Rather,refueling lock 245 may prevent the insertion of a refueling pump intofuel filler pipe 211. The filler pipe valve may be electrically locked,for example by a solenoid, or mechanically locked, for example by apressure diaphragm.

In some embodiments, refueling lock 245 may be a refueling door lock,such as a latch or a clutch which locks a refueling door located in abody panel of the vehicle. The refueling door lock may be electricallylocked, for example by a solenoid, or mechanically locked, for exampleby a pressure diaphragm.

In embodiments where refueling lock 245 is locked using an electricalmechanism, refueling lock 245 may be unlocked by commands fromcontroller 212, for example, when a fuel tank pressure decreases below apressure threshold. In embodiments where refueling lock 245 is lockedusing a mechanical mechanism, refueling lock 245 may be unlocked via apressure gradient, for example, when a fuel tank pressure decreases toatmospheric pressure.

Emissions control system 251 may include one or more emissions controldevices, such as one or more fuel vapor canisters 222 filled with anappropriate adsorbent, the canisters are configured to temporarily trapfuel vapors (including vaporized hydrocarbons) during fuel tankrefilling operations, “running loss” (that is, fuel vaporized duringvehicle operation), and diurnal cycles. In one example, the adsorbentused is activated charcoal. Emissions control system 251 may furtherinclude a canister ventilation path or vent line 227 which may routegases out of the canister 222 to the atmosphere when storing, ortrapping, fuel vapors from fuel system 218.

Canister 222 may include a buffer 222 a (or buffer region), each of thecanister and the buffer comprising the adsorbent. As shown, the volumeof buffer 222 a may be smaller than (e.g., a fraction of) the volume ofcanister 222. The adsorbent in the buffer 222 a may be same as, ordifferent from, the adsorbent in the canister (e.g., both may includecharcoal). Buffer 222 a may be positioned within canister 222 such thatduring canister loading, fuel tank vapors are first adsorbed within thebuffer, and then when the buffer is saturated, further fuel tank vaporsare adsorbed in the canister. In comparison, during canister purging,fuel vapors are first desorbed from the canister (e.g., to a thresholdamount) before being desorbed from the buffer. In other words, loadingand unloading of the buffer is not linear with the loading and unloadingof the canister. As such, the effect of the canister buffer is to dampenany fuel vapor spikes flowing from the fuel tank to the canister,thereby reducing the possibility of any fuel vapor spikes going to theengine. One or more temperature sensors 232 may be coupled to and/orwithin canister 222. As fuel vapor is adsorbed by the adsorbent in thecanister, heat is generated (heat of adsorption). Likewise, as fuelvapor is desorbed by the adsorbent in the canister, heat is consumed. Inthis way, the adsorption and desorption of fuel vapor by the canistermay be monitored and estimated based on temperature changes within thecanister.

Vent line 227 may also allow fresh air to be drawn into canister 222when purging stored fuel vapors from fuel system 218 to engine intake223 via purge line 228 and purge valve 261. For example, purge valve 261may be normally closed but may be opened during certain conditions sothat vacuum from engine intake manifold 244 is provided to the fuelvapor canister for purging. In some examples, vent line 227 may includean air filter 259 disposed therein upstream of a canister 222.

In some examples, the flow of air and vapors between canister 222 andthe atmosphere may be regulated by a canister vent valve (CVV) 297coupled within vent line 227. The canister vent valve may be a normallyopen valve, so that fuel tank isolation valve 252 (FTIV) may controlventing of fuel tank 220 with the atmosphere. FTIV 252 may be positionedbetween the fuel tank and the fuel vapor canister within conduit 278.FTIV 252 may be a normally closed valve, that when opened, allows forthe venting of fuel vapors from fuel tank 220 to canister 222. Fuelvapors may then be vented to atmosphere, or purged to engine intakesystem 223 via canister purge valve 261.

Fuel system 218 may be operated by controller 212 in a plurality ofmodes by selective adjustment of the various valves and solenoids. Forexample, the fuel system may be operated in a fuel vapor storage mode(e.g., during a fuel tank refueling operation and with the engine notrunning), wherein the controller 212 may open isolation valve 252 whileclosing canister purge valve (CPV) 261 to direct refueling vapors intocanister 222 while preventing fuel vapors from being directed into theintake manifold.

As another example, the fuel system may be operated in a refueling mode(e.g., when fuel tank refueling is requested by a vehicle operator),wherein the controller 212 may open isolation valve 252, whilemaintaining canister purge valve 261 closed, to depressurize the fueltank before allowing enabling fuel to be added therein. As such,isolation valve 252 may be kept open during the refueling operation toallow refueling vapors to be stored in the canister. After refueling iscompleted, the isolation valve may be closed.

As yet another example, the fuel system may be operated in a canisterpurging mode (e.g., after an emission control device light-offtemperature has been attained and with the engine running), wherein thecontroller 212 may open canister purge valve 261 while closing isolationvalve 252. Herein, the vacuum generated by the intake manifold of theoperating engine may be used to draw fresh air through vent 227 andthrough fuel vapor canister 222 to purge the stored fuel vapors intointake manifold 244. In this mode, the purged fuel vapors from thecanister are combusted in the engine. The purging may be continued untilthe stored fuel vapor amount in the canister is below a threshold.

Controller 212 may comprise a portion of a control system 214. Controlsystem 214 is shown receiving information from a plurality of sensors216 (various examples of which are described herein) and sending controlsignals to a plurality of actuators 281 (various examples of which aredescribed herein). As one example, sensors 216 may include exhaust gassensor 237 located upstream of the emission control device, temperaturesensor 233, pressure sensor 291 (fuel tank pressure transducer), andcanister temperature sensor 232. Other sensors such as pressure,temperature, air/fuel ratio, and composition sensors may be coupled tovarious locations in the vehicle system 206. As another example, theactuators may include fuel injector 266, throttle 262, fuel tankisolation valve 252, CVV 297, CPV 261 and refueling lock 245. Thecontroller 212 may receive input data from the various sensors, processthe input data, and trigger the actuators in response to the processedinput data based on instruction or code programmed therein correspondingto one or more routines. An example control routine is described hereinwith regard to FIG. 4.

Evaporative emissions detection routines may be intermittently performedby controller 212 on fuel system 218 and emissions control system 251 toconfirm that the fuel system and/or emissions control system is notdegraded. As such, evaporative emissions detection routines may beperformed while the engine is off (engine-off evaporative emissionstest) using engine-off natural vacuum (EONV) generated due to a changein temperature and pressure at the fuel tank following engine shutdownand/or with vacuum supplemented from a vacuum pump. Alternatively,evaporative emissions detection routines may be performed while theengine is running by operating a vacuum pump and/or using engine intakemanifold vacuum. Evaporative emissions tests may be performed by anevaporative level check monitor (ELCM) 295 communicatively coupled tocontroller 212. ELCM 295 may be coupled in vent 227, between canister222 and the atmosphere. ELCM 295 may include a vacuum pump for applyingnegative pressure to the fuel system and/or emissions control systemwhen administering an evaporative emissions test. In some embodiments,the vacuum pump may be configured to be reversible. In other words, thevacuum pump may be configured to apply either a negative pressure or apositive pressure on the fuel system and/or emissions control system.ELCM 295 may further include a reference orifice and a pressure sensor296. Following the applying of vacuum to the fuel system and/oremissions control system, a change in pressure at the reference orifice(e.g., an absolute change or a rate of change) may be monitored andcompared to a threshold. Based on the comparison, a fuel system and/oremissions control system may be diagnosed for undesired evaporativeemissions.

In some configurations, a canister vent valve (CVV) 297 may be coupledwithin vent line 227. CVV 297 may function to adjust a flow of air andvapors between canister 222 and the atmosphere. The CVV may also be usedfor diagnostic routines. When included, the CVV may be opened duringfuel vapor storing operations (for example, during fuel tank refuelingand while the engine is not running) so that air, stripped of fuel vaporafter having passed through the canister, can be pushed out to theatmosphere. Likewise, during purging operations (for example, duringcanister regeneration and while the engine is running), the CVV may beopened to allow a flow of fresh air to strip the fuel vapors stored inthe canister. In some examples, CVV 297 may be a solenoid valve whereinopening or closing of the valve is performed via actuation of a canistervent solenoid. In particular, the canister vent valve may be a defaultopen valve that is closed upon actuation of the canister vent solenoid.In some examples, CVV 297 may be configured as a latchable solenoidvalve. In other words, when the valve is placed in a closedconfiguration, it latches closed without requiring additional current orvoltage. For example, during the conducting of a diagnostic evaporativeemissions detection routine, CVV 297 may be placed in a closedconfiguration to isolate emissions control system 251 from atmosphere,with CPV 261 maintained closed. In another example, closing CVV 297 andopening isolation valve 252 during a diagnostic evaporative emissionsdetection routine may couple the fuel system 218 and emissions controlsystem 251, wherein the coupled fuel system 218 and emissions controlsystem 251 are isolated from atmosphere, with CPV 261 maintained closed.

As described above, in conducting diagnostic evaporative emissionsroutines, the entire emissions control system 251 and fuel system 218must be diagnosed for potential undesired emissions. However, forevaporative emissions routines that take place while the vehicle is notin operation, but rather is in park, certain parking conditions mayresult in the closing of fuel tank valves, for example FLVV 285, and GVV283, depending on the level of fuel in the tank and the vehicle compoundangle. The closing of FLVV 285 and GVV 283 may thus restrictcommunication between fuel system 218 and emissions control system 251,wherein the fuel tank/fuel system may not be properly checked forundesired emissions during the test diagnostic. In another example, theformation of an isolated vapor dome space(s) may occur as a result ofcertain parking conditions depending on the fuel tank geometry and thelevel of fuel in the tank. As any areas of the emissions control system251 and fuel system 218 that go unchecked violate regulatoryrequirements for evaporative emissions testing, it is desirable tomitigate the potential issues with conducting evaporative emissionsroutines where parking conditions including vehicle compound angle andfuel level may result in particular areas of the fuel system goingundiagnosed.

Turning now to FIG. 3A, a vehicle parking condition 300 is illustrated.Vehicle 305 is shown parked on an inclined surface 375. Inertial sensors380 (e.g., 199 in FIG. 1) may enable a determination of the vehiclecompound angle. For example, inertial sensors may include longitudinal381 (X), latitudinal 383 (Y), vertical 386 (Z), roll 382, pitch 384, andyaw 386 sensors. In other words, inertial sensors may enable vehicleposition information comprising six degrees of freedom. Based on thesignals acquired from inertial sensors 380, it may be determined whetherthe vehicle compound angle may result in fuel system isolation (e.g.,218 in FIG. 2) from the emissions control system (e.g., 251 in FIG. 2),or the formation of an isolated fuel tank vapor dome(s). Thedetermination may be based on the signals acquired from inertial sensors380, an indicated fuel level in the fuel tank, and computer aided design(CAD) modeling of the particular fuel tank installed in vehicle 305. Asone example, a 2D lookup table may be stored in the vehicle controlsystem memory such that, for a vehicle compound angle determined frominertial sensors 380 and a fuel level it may be indicated whether thevehicle compound angle and fuel level is equal to or greater than apredetermined threshold. In other words, it may be determined whetherthe fuel system may be restricted from the emissions control system,and/or whether one or more section(s) of the fuel tank may be isolatedfrom other sections of the fuel tank (e.g., isolated vapor domeformation).

Turning to FIG. 3B, an example illustration is shown depicting asituation where a vehicle parking condition is resulting in the fuelsystem 218 being isolated from the emission control system. Componentsthat are the same as those illustrated in FIG. 2 are denoted by the samereference number. Illustrated in FIG. 3B, fuel system 218 is depicted asbeing inclined at the same vehicle compound angle as vehicle 305illustrated in FIG. 3A. The fuel level 277 in the fuel tank 220 is suchthat, at the indicated fuel tank position, FLVV 285 and GVV 283 areunintentionally closed (also referred to as corking). As such, if anevaporative emissions test diagnostic were conducted, the fuel tankwould be restricted from the analysis. As described above, with regardto FIG. 3A, based on signals acquired from inertial sensors 380, alongwith indicated fuel level 277, it may be predicted that FLVV 285 and GVV283 are likely to be unintentionally closed under the given parkingconditions. As such, prior to conducting an evaporative emissions test,mitigating actions may first be taken, as described below.

Turning to FIG. 3C, an example illustration is shown depicting a vehicle305 under parking conditions as described in FIG. 3A, but wherein thevehicle's active suspension is employed to level the vehicle by adetermined amount. Components that are the same as those illustrated inFIG. 3A are denoted by the same reference number. More specifically,vehicle 305 is shown parked on an inclined surface 375. Based on thesignals acquired from inertial sensors 380 (vehicle compound angle),combined with indicated fuel level, it may be determined that thevehicle parking condition is resulting in restriction of the fuel systemand/or resulting in an isolated fuel tank vapor dome(s). As such,evaporative emissions testing may not proceed until mitigating action isundertaken. Mitigating action may include determining an amount ofleveling of the vehicle that may be required to level the fuel in thefuel tank such that the fuel system is no longer restricted from theemissions control system. In other words, the mitigating action mayinclude calculating the determined amount of leveling based on thevehicle compound angle and the fuel level, and leveling the vehicleuntil the fuel tank valve(s) are open and/or no section of the fuel tankis isolated from another section of the fuel tank (e.g. no isolatedvapor dome(s)). As described in FIG. 3A, the determination may be basedon the signals acquired from inertial sensors 380, an indicated fuellevel in the fuel tank, and computer aided design (CAD) modeling of theparticular fuel tank installed in vehicle 305. For example, a 2D lookuptable may be stored in the vehicle control system memory such that, foran indicated vehicle compound angle determined from inertial sensors380, and an indicated fuel level, an amount of leveling may be indicatedsuch that the fuel tank is no longer restricted from the emissionscontrol system. As indicated in FIG. 3C, a determined leveling amount ofthe vehicle, indicated by arrow 376, may be accomplished via theemployment of the vehicle's active suspension, such as active suspension111 described in FIG. 1.

Turning now to FIG. 3D, an example illustration is shown depicting asituation where a vehicle leveling event resulting in the fuel system218 being no longer restricted from the emission control system and/orthe elimination of an isolated fuel tank vapor dome. Components that arethe same as those illustrated in FIG. 2 (and FIG. 3B) are denoted by thesame reference number. Illustrated in FIG. 3D, fuel system 218 isdepicted as being leveled by the same amount as the vehicle 305illustrated in FIG. 3C. Subsequent to the fuel tank leveling event, thefuel level 277 in the fuel tank 220 is such that, FLVV 285 and GVV 283are no longer corked shut. As such, an evaporative emissions test mayproceed.

Turning to FIG. 4, a flow chart for an example method 400 for leveling avehicle a determined amount prior to conducting an evaporative emissionstest is shown. More specifically, method 400 may be used to indicatewhether a vehicle parking condition is likely to result in unintentionalclosing of fuel tank valves, such as FLVV (e.g., 285) and GLVV (e.g.,283) such that the fuel system is restricted from the emissions controlsystem and/or whether isolated vapor dome(s) may be formed in the fueltank resulting from the vehicle parking condition. The indication thatthe fuel tank may be restricted from the emissions control, or thatisolated vapor dome(s) may be formed may be based on on-board inertialsensors, combined with an indicated level of fuel in the fuel tank. If avehicle parking condition based on a vehicle compound angle and a fuellevel is predicted to result in the fuel tank being restricted from theemissions control system, or if the formation of fuel tank vapor domesare predicted, method 400 includes leveling the vehicle a determinedamount via the employment of the vehicle's active suspension system,prior to conducting an evaporative emissions test. Subsequent to thecompletion of the evaporative emissions test, the vehicle's activesuspension system may be further employed to return the vehicle to adefault state. In this way, method 400 may enable the conduction ofevaporative emissions tests under conditions where no areas of theemissions control system and the fuel system go unchecked and thusviolation of regulatory requirements may be reduced. Further, method 400may increase opportunities for evaporative emission testing and thusresult in a reduction in bleed emissions. Method 400 will be describedwith reference to the systems described herein and shown in FIGS. 1-3,though it should be understood that similar methods may be applied toother systems without departing from the scope of this disclosure.Method 400 may be carried out by a controller holding executableinstructions in non-transitory memory, such as controller 12 in FIG. 2.

Method 400 begins at 402 and includes evaluating current operatingconditions. Operating conditions may be estimated, measured, and/orinferred, and may include one or more vehicle conditions, such asvehicle speed, vehicle location, etc., various engine conditions, suchas engine status, engine load, engine speed, A/F ratio, etc., variousfuel system conditions, such as fuel level, fuel type, fuel temperature,etc., various evaporative emissions system conditions, such as fuelvapor canister load, fuel tank pressure, etc., as well as variousambient conditions, such as ambient temperature, humidity, barometricpressure, etc. At 404, method 400 includes determining whether avehicle-off event has occurred. The vehicle-off event may include anengine-off event, and may be indicated by other events, such as akey-off event. The vehicle-off event may follow a vehicle run timeduration, the vehicle run time duration commencing at a previousvehicle-on event. If no vehicle-off event is detected, method 400proceeds to 406. At 406, method 400 includes recording that anevaporative emissions test was not executed, and may further includesetting a flag to retry the evaporative emissions test at the nextdetected vehicle-off event. Method 400 then ends.

If a vehicle-off event is detected, method 400 may proceed to 408. At408, method 400 may include determining whether entry conditions for anevaporative emissions test are met. Entry conditions for the evaporativeemissions detection routine may include a variety of engine and/or fuelsystem operating conditions and parameters. Additionally, in the casewhen the engine is included in a hybrid electric vehicle, entryconditions for evaporative emissions detection may include a variety ofvehicle conditions. For example, entry conditions for evaporativeemissions detection may include an amount of time since a priorevaporative emissions testing. For example, evaporative emissionstesting may be performed on a set schedule, e.g., evaporative emissionsdetection may be performed after a vehicle has traveled a predeterminednumber of miles since a previous evaporative emissions test or after apredetermined duration has passed since a previous evaporative emissionstest.

As another example, entry conditions for evaporative emissions detectionmay include a temperature of one or more fuel system components being ina predetermined temperature range. For example, temperatures which aretoo hot or too cold may decrease accuracy of evaporative emissionsdetection. Such a temperature range may depend on the method used tocalculate the evaporative emissions detection and the sensors employed.However, in some examples, evaporative emissions detection may occur atany temperature.

As another example, entry conditions for evaporative emissions detectionmay include whether or not undesired evaporative emissions haspreviously been detected. For example, if undesired evaporativeemissions was detected by a prior evaporative emissions test, thenevaporative emissions testing may not be performed, e.g., until theundesired evaporative emissions is fixed and an onboard diagnosticsystem code has been reset. Alternatively, if undesired evaporativeemissions was detected by a prior evaporative emissions test,evaporative emissions testing may be repeated after a predetermined timeor distance traveled to validate or invalidate the presence of undesiredevaporative emissions. As another example, entry conditions forevaporative emissions detection may include if a refueling event istaking place. For example, evaporative emissions detection may not beperformed while the fuel tank is being refilled or when the fuel cap isoff, etc.

As another example, entry conditions for evaporative emissions detectionmay include an amount of available energy stored, e.g., in an energystorage device, to run a vacuum or positive pressure pump. Thus, it maybe confirmed if the state of charge, voltage, etc. of the battery issuch that sufficient energy is available to perform the evaporativeemissions test.

For an engine-off natural vacuum test, the engine must be at rest withall cylinders off, as opposed to engine operation with the enginerotating, even if one or more cylinders are deactivated. Further entryconditions may include a threshold amount of time passed since theprevious EONV test, a threshold length of engine run time prior to theengine-off event, a threshold amount of fuel in the fuel tank, and athreshold battery state of charge. For example, entry into an EONV testmay be based on an amount of heat rejected by the engine during theprevious drive cycle, the timing of the heat rejected, the length oftime spent at differing levels of drive aggressiveness, ambientconditions, etc. The heat rejected by the engine may be inferred basedon or more of engine load, fuel injected summed over time, intakemanifold air mass summed over time, miles driven, etc. Further, entryconditions may be based on an ambient temperature and a fuel level. Theambient temperature may be estimated, inferred, and/or measured via anambient temperature sensor, retrieved from an off-board weather server,etc. Fuel level may be determined by a fuel level sensor, located in thefuel tank, and may comprise a float connected to a variable resistor,such as fuel level sensor 234 depicted in FIG. 2. Alternatively, othertypes of fuel level sensors may be used.

As another example, entry conditions for evaporative emissions detectionmay include an indication that the vehicle is not occupied. For example,the indication that the vehicle is not occupied may include one or moreof a powertrain control module query of seat load cells (e.g., 103 inFIG. 1), door sensing technology (e.g., 104 in FIG. 1), onboard cameras(e.g., 105 in FIG. 1), etc. In some examples, commencing the evaporativeemissions test may be subsequent to an indication that the vehicle isnot occupied.

If at 408 entry conditions as described above are not met, method 400may proceed to 406. At 406, method 400 may include recording that anevaporative emissions test was not executed, and may further includesetting a flag to retry the evaporative emissions test at the nextdetected vehicle-off event. Method 400 may then end.

If entry conditions for an evaporative emissions test are met at 408,method 400 may proceed to 410. At 410, method 400 may includecalculating a vehicle compound angle (also referred to as a vehiclepitch and bank) and a fuel level. As described above, inertial sensors(e.g., 199 in FIG. 1) may enable a determination of the vehicle compoundangle. For example, as described with regard to FIG. 3, inertial sensorsmay include longitudinal 381 (X), latitudinal 383 (Y), vertical 386 (Z),roll 382, pitch 384, and yaw 386 sensors. As such, vehicle compoundangle, may be calculated at 410. Further, fuel level may be indicated at410 via input from a fuel level sensor (e.g., fuel level sensor 234 inFIG. 2).

Following calculation of the vehicle compound angle and fuel level,method 400 may proceed to 411. At 411, method 400 includes determiningwhether the vehicle parking condition may result in fuel systemisolation (e.g., 218 in FIG. 2) from the emissions control system (e.g.,251 in FIG. 2), or the formation of one or more isolated fuel tank vapordome(s). As described above with regard to FIG. 3A, the determinationmay be based on the signals acquired from inertial sensors 380, anindicated fuel level in the fuel tank, and computer aided design (CAD)modeling of the particular fuel tank installed in the vehicle. As such,a 2D lookup table may be stored in the vehicle control system memorywherein an indicated vehicle compound angle determined at 410, may becompared to an indicated fuel level, and if the compound angle and fuellevel is equal to or greater than a predetermined threshold, it may beindicated that the fuel system may be restricted from the emissionscontrol system, and/or isolated fuel tank vapor dome(s) may result(e.g., one or more sections of the fuel tank may be isolated from othersections of the fuel tank).

If at 411 if it is indicated that fuel system isolation is not likely tooccur based on the vehicle compound angle and indicated fuel level,method 400 may proceed to 412. At 412, method 400 may include conductingan evaporative emissions test without any mitigating action. Forexample, at 411 it may be indicated that the vehicle is parked on asteep and banked slope, but that the fuel level in the fuel tank is suchthat no fuel system isolation may result. In other examples, at 411 itmay be indicated that the vehicle is parked on a flat surface, thus eventhough fuel level may be high, no fuel system isolation may result. Assuch, at 412, conducting an evaporative emissions test may proceed withno mitigating action. At 412, a vehicle-off evaporative emissions testmay be conducted in any manner conventionally known in the art. In oneexample an engine-off natural vacuum emissions test may be conducted. Assuch, method 412 may include closing a CVV (e.g., 297 in FIG. 2), andopening an FTIV (e.g., 252 in FIG. 2) in order to couple the fuel system(e.g., 218 in FIG. 2) with the emissions control system (e.g., 251 inFIG. 2), wherein the coupled fuel system and emissions control systemmay be sealed from atmosphere. Subsequent to isolating the fuel systemand emissions control system from atmosphere, a pressure build may bemonitored for a duration. For example, if sufficient heat was rejectedto the fuel tank during the previous drive cycle, pressure in the fuelsystem and emissions control system may increase as liquid fuelvaporizes. If the pressure builds to a predetermined threshold level,the evaporative emissions test may pass on the pressure build.Alternatively, if the pressure builds to a level below a predeterminedthreshold level, and plateaus, the CVV may be opened to allow for thepressure in the fuel system and emissions control system to return toatmospheric pressure. Following the return to atmospheric pressure, theCVV may again be closed to seal the emissions control system and fuelsystem, and the development of vacuum build may be monitored for aduration as a result of the cooling of the fuel tank. Development of afuel system and/or emissions control system vacuum equal to or greaterthan a predetermined threshold vacuum level may indicate a passingresult. However, if the level of vacuum does not build to a thresholdlevel, undesired emissions may be indicated.

As an alternative to the above-described EONV evaporative emissionstest, at 412 an evaporative emissions test may instead be conducted viathe use of a pump configured to evacuate and/or pressurize the fuelsystem and emissions control system. For example, at 412, the emissionscontrol system may be coupled to the fuel system via the opening of theFTIV, and the coupled emissions control system and fuel system sealedfrom atmosphere via the closing of the CVV. Subsequently, a pump (e.g.,295 in FIG. 2) may be used to pressurize the coupled fuel system andemissions control system to a predetermined level. Following thepressurization of the fuel system and emissions control system, pressuremay be monitored for a duration. If the system is free of undesiredevaporative emissions, the pressure level may not decline past apredetermined threshold level. Alternatively, if undesired evaporativeemissions are indicated, the pressure level may decline past thepredetermined threshold. In other examples, the coupled fuel system andemissions control system may be evacuated until a predetermined vacuumlevel is reached. Following the attainment of a predetermined vacuumlevel, the coupled fuel system and emissions control system may besealed from atmosphere, and pressure monitored for a duration. If thevacuum does not decline past a predetermined threshold, then it may beindicated that undesired evaporative emissions are not present.Alternatively, if the level of vacuum declines past the predeterminedthreshold level, undesired evaporative emissions may be indicated.

It may be understood that the above description of EONV evaporativeemissions test procedures, along with the above description ofevaporative emissions test procedures using an external pressure and/orvacuum source, may be conducted in any such fashion as is conventionallyknown in the art. In other words, the above descriptions of exampleevaporative emissions test procedures are meant to be informative, andnot limiting in any way.

As such, at 412, method 400 includes conducting an evaporative emissionstest procedure by any manner as is conventionally known in the art.However, although entry conditions may be met at the initiation ofmethod 400 conditions may change during the execution of the method. Forexample, for an emissions test being conducted without leveling, avehicle becoming occupied, an engine restart, or a refueling event maybe sufficient to abort the method at any point prior to completingmethod 400. As such, if such events are detected at 413 that wouldinterfere with the performing of method 400 or the interpretation ofresults derived from executing method 400, method 400 may proceed to 414and abort the test, record that an evaporative emissions test wasaborted, and proceed to 406 in order to set a flag to retry theevaporative emissions test at the next detected vehicle-off event, andthen end.

If a vehicle becoming occupied (or a refueling event, etc.) is notdetected during the conducting of the evaporative emissions test, method400 proceeds to 415 and includes recording the results of the test. Forexample, recording the outcome of the test may include recording apassing result of the evaporative emissions test at the controller, orrecording a failing result of the evaporative emissions test at thecontroller. Responsive to a failing result of the evaporative emissionstest, at 412, recording the result may include setting a flag at thecontroller and activating an MIL to indicate the vehicle operator of thepresence of undesired evaporative emissions.

Subsequent to the conducting of an evaporative emissions test procedureat 412 and recording the result at the controller, method 400 mayproceed to 416. At 416, method 400 may include updating an evaporativeemissions system and fuel system status to reflect the passing orfailing result of the evaporative emissions test. For example,responsive to a passing result from an evaporative emissions testwherein undesired emissions are not indicated, updating emissionscontrol system and fuel system status may include updating theevaporative emissions test schedule. For example, scheduled evaporativeemissions tests may be delayed or adjusted based on the passing testresult. Alternatively, responsive to a failing evaporative emissionstest result at 412, updating emissions control system and fuel systemstatus may include adjusting engine operating parameters to reflect anindication of undesired emissions in the fuel system and/or emissionscontrol system. For example, adjusting engine operating parameters mayinclude adjusting a maximum engine load to reduce fuel consumption,adjusting a commanded A/F ratio, operating the vehicle in battery-onlymode during certain conditions, etc. Method 400 may then end.

Returning to 411, if it is indicated that fuel system isolation mayoccur based on the indicated vehicle compound angle, along with anindicated fuel level, method 400 may proceed to 418. At 418, method 400may include calculating a corrective leveling amount wherein by levelingthe vehicle by the calculated amount, fuel system isolation may bemitigated. As described above with regard to FIG. 3C, a correctiveleveling amount may be determined based on the signals acquired frominertial sensors 380, an indicated fuel level in the fuel tank, andcomputer aided design (CAD) modeling of the particular fuel tankinstalled in vehicle 305. For example, a 2D lookup table may be storedin the vehicle control system memory such that, for an indicated vehiclecompound angle determined from inertial sensors 380, and an indicatedfuel level, an amount of leveling may be indicated such that the fueltank is no longer restricted from the emissions control system. In otherwords, calculating the corrective leveling amount at 418 may includecalculating the amount based on the vehicle compound angle and the fuellevel where the indicated leveling may result in the one or more fueltank valve(s) being open and/or where no section of the fuel tank isisolated from another section of the fuel tank.

Proceeding to 420, method 400 may include indicating whether theleveling amount indicated at 418 is greater than a predeterminedthreshold. For example, the amount of leveling required to correct thefuel system isolation must be within the capacity of the vehicle activesuspension system. If at 420 it is determined that the indicated amountof vehicle leveling in order to correct the fuel tank isolation exceedsthe capabilities of the vehicle active suspension system, method 400 mayproceed to 422. At 422, method 400 may include recording that anevaporative emissions test was not executed, and may further includesetting a flag to retry the evaporative emissions test at the nextdetected vehicle-off event. Method 400 may then end.

Returning to 420, if it is determined that the leveling amount requiredto correct the fuel tank isolation does not exceed the capabilities ofthe vehicle active suspension system, method 400 may proceed to 424. At424, method 400 may include leveling the vehicle the amount determinedamount at 418. For example, at 424, the vehicle's active suspensionsystem (e.g., 111 in FIG. 1) may be employed to level the vehicle inaccordance with an indicated corrective amount according to the vehiclecompound angle and fuel level. As described above with regard to FIG. 1,active suspension system 111 may comprise an active suspension systemhaving hydraulic, electrical, and/or mechanical devices, as well asactive suspension systems that control the vehicle height on anindividual corner basis (e.g., four corner independently controlledvehicle heights), and/or on an axle-by-axle basis (e.g., front axle andrear axle vehicle heights), etc.

Subsequent to leveling the vehicle at 424, method 400 may proceed to426. At 426, method 400 may include conducting an evaporative emissionstest procedure. At 426, a vehicle-off evaporative emissions test may beconducted in any manner conventionally known in the art. In one examplean engine-off natural vacuum emissions test may be conducted, asdescribed above in detail with regard to step 412 of method 400. Inanother example, as an alternative to the above-described EONVevaporative emissions test, at 426 an evaporative emissions test mayinstead be conducted via the use of a pump configured to evacuate and/orpressurize the fuel system and emissions control system, as describedabove in detail with regard to step 412 of method 400. It may beunderstood that the above description of EONV evaporative emissions testprocedures, along with the above description of evaporative emissionstest procedures using an external pressure and/or vacuum source, may beconducted at step 426 of method 400 in any such fashion as isconventionally known in the art. In other words, the above descriptionsof example evaporative emissions test procedures are meant to beinformative, and not limiting in any way.

As such, at 426, method 400 includes conducting an evaporative emissionstest procedure by any manner as is conventionally known in the art.However, as described above, although entry conditions may be met at theinitiation of method 400 conditions may change during the execution ofthe method. For example, for an emissions test being conductedsubsequent to leveling, a vehicle becoming occupied, an engine restart,or a refueling event may be sufficient to abort the method at any pointprior to completing method 400. As such, if such events are detected at428 that would interfere with the performing of method 400 or theinterpretation of results derived from executing method 400, method 400may proceed to 430 and abort the test, record that an evaporativeemissions test was aborted, return the vehicle to default conditionsprior to the commencing of the evaporative emissions test, and proceedto 422 in order to set a flag to retry the evaporative emissions test atthe next detected vehicle-off event, and then end.

If a vehicle becoming occupied (or a refueling event, etc.) is notdetected during the conducting of the evaporative emissions test, method400 proceeds to 431 and includes recording the results of the test. Forexample, recording the outcome of the test may include recording apassing result of the evaporative emissions test at the controller, orrecording a failing result of the evaporative emissions test at thecontroller. Responsive to a failing result of the evaporative emissionstest, at 426, recording the result may include setting a flag at thecontroller and activating an MIL to indicate the vehicle operator of thepresence of undesired evaporative emissions.

Proceeding to 432, method 400 includes returning the vehicle to defaultparking conditions subsequent to completion of the evaporative emissionstest procedure. For example, at 432, returning the vehicle to defaultconditions may include employing the vehicle's active suspension system(e.g., 111 in FIG. 1) to return the vehicle to default (also referred toherein as pre-leveling) conditions. However, in other examples, method400 may include not returning the vehicle to default parking conditionssubsequent to completion of the evaporative emissions test procedure.For example, subsequent to completion of the evaporative emissions testprocedure, the vehicle may be maintained at the level for which thevehicle was maintained during the evaporative emission test.

Following returning the vehicle to pre-leveling conditions at 432,method 400 may proceed to 416. At 416, method 400 may include updatingemission control system and fuel system status. At 416, method 400 mayinclude updating an evaporative emissions system and fuel system statusto reflect the passing or failing result of the evaporative emissionstest. For example, responsive to a passing result from an evaporativeemissions test wherein undesired emissions are not indicated, updatingemissions control system and fuel system status may include updating theevaporative emissions test schedule. For example, scheduled evaporativeemissions tests may be delayed or adjusted based on the passing testresult. Alternatively, responsive to a failing evaporative emissionstest result at 431, updating emissions control system and fuel systemstatus may include adjusting engine operating parameters to reflect anindication of undesired emissions in the fuel system and/or emissionscontrol system. For example, adjusting engine operating parameters mayinclude adjusting a maximum engine load to reduce fuel consumption,adjusting a commanded A/F ratio, operating the vehicle in battery-onlymode during certain conditions, etc. Method 400 may then end.

In some examples, certain parameters of the evaporative emissions testdetailed in method 400 may change depending on whether the evaporativeemissions test is conducted without leveling the vehicle, as compared tothe evaporative emissions test conducted via leveling of the vehicle. Inother words, certain parameters of the evaporative emissions test may bedifferent if conducted at 412 of method 400 compared to 426 of method400. In one example, leveling of the vehicle at 426 may result insignificant sloshing of the fuel in the fuel tank. As such, for an EONVevaporative emissions test, the passing threshold for the pressure buildportion and/or vacuum build portion of the EONV test may be adjusted toaccount for the increased pressure in the fuel tank generated by thesloshing of fuel resulting from leveling the vehicle at 424. In somecases the adjusted threshold may be an absolute threshold. In othercases the adjusted threshold may comprise an adjusted threshold rate. Inother examples, such as an evaporative emissions test conducted via theexternal pressurization and/or evacuation of the fuel system andemissions control system, certain parameters of the evaporativeemissions test may similarly be different if conducted at 412 of method400 compared to 426 of method 400. For example, as described above, theact of leveling the vehicle at 424 of method 400 may result insignificant sloshing of fuel in the fuel tank. As such, the increasedlevel of pressure in the fuel system and/or emissions control system mayaffect the results of a pressure or vacuum-based evaporative emissionstest conducted via an external source. Therefore, in one example, priorto conducting an evaporative emissions test at 426 subsequent toleveling the vehicle, the pressure in the fuel system and/or emissionscontrol system may first need to be stabilized prior to conducting theevaporative emissions test. In one example, the period of time forstabilization may be greater for conducting an evaporative emissionstest at 426 than a period of time for stabilization for conducting anevaporative emissions test at 412.

The above examples of parameters that may change as a result of theevaporative emissions test detailed in method 400 being conductedwithout leveling the vehicle, as compared to the evaporative emissionstest conducted via leveling of the vehicle are meant to be illustrativeand not limiting in any way. For example, any number of parameters maychange accordingly based on vehicle compound angle and fuel level, inconjunction with the presence or absence of leveling of the vehicleprior to conducting the evaporative emissions test.

FIG. 5 shows an example timeline 500 for determining whether a vehicleparking condition may result in fuel system isolation, and if so,leveling the vehicle a determined amount prior to conducting anevaporative emissions test procedure according to the methods describedherein and with reference to FIG. 4, and as applied to the systemsdescribed herein and with reference to FIGS. 1-3. Timeline 500 includesplot 505, indicating whether a vehicle-off event is detected over time,and plot 510, indicating a fuel tank fuel level over time. Timeline 500further includes plot 515, indicating a percent road grade (e.g., roadcompound angle) over time, and plot 520, indicating a vehicle grade(e.g., vehicle compound angle), over time. Line 525 represents a firstthreshold where above the threshold fuel tank isolation may result, thethreshold based on the vehicle parking condition (e.g., vehicle compoundangle or vehicle pitch angle and bank angle), and fuel level, indicatedby plot 510. Line 530 represents a second threshold where above thethreshold fuel tank isolation may result, the threshold similarly basedon the on the vehicle parking condition (e.g., vehicle compound angle orvehicle pitch angle and bank angle), and fuel level. Timeline 500further includes plot 535, indicating the status of a canister ventvalve (CVV), over time. Timeline 500 further includes plot 540,indicating a pressure monitored by a fuel tank pressure transducer(FTPT), such as FTPT 291 in FIG. 2. Line 545 represents a predeterminedthreshold pressure, below which undesired emissions may be indicatedduring an EONV evaporative emissions test procedure. Line 550 representsa predetermined vacuum threshold, above which undesired emissions may beindicated during an EONV evaporative emission test procedure. Whiletimeline 500 indicates an evaporative emissions test comprising an EONVtest procedure, it should be understood that any suitable evaporativeemissions test procedure may be employed without departing from thescope of this disclosure. Timeline 500 further includes plot 555,indicating whether undesired emissions are indicated, over time.

At time t₀ the vehicle is in operation, indicated by plot 505. Fuellevel in the fuel tank is near full, indicated by plot 510. The vehicleis traveling along a flat road where the road grade is a definedpercentage, indicated by plot 515. As such, the vehicle grade, orcompound angle, indicated by plot 520 and determined by inertial sensors(e.g., 199 in FIG. 1), is indicated to be the same percentage grade asthe road grade percentage. As the vehicle is in operation, the CVV isopen, indicated by plot 535. As such, pressure in the emissions controlsystem and fuel system, as monitored by FTPT, is at atmosphere. In someexamples, as described above with regard to method 400, a vehicle may beconfigured with a FTIV, such as FTIV 252 (FIG. 1). In such a case,control over the coupling between the fuel system and the emissioncontrol system may be enabled. However, in this example, the FTIV isexcluded as not all vehicles may be configured with and FTIV. As such,in this example timeline 500, the fuel system may be considered coupledto the emissions control system. As such, by opening the CVV, asdescribed, FTPT indicates atmospheric pressure. Further, at time to,undesired emissions are not indicated, indicated by plot 555.

Between time t₀ and t₁ the vehicle remains in operation, and ascends ahill, indicated by plot 515. As such, inertial sensors indicate thevehicle is traveling up a hill, indicated by plot 520. As the vehicle isin operation, fuel level slightly declines.

At time t₁ a vehicle-off event is detected, indicated by plot 505. Asthe vehicle-off event has occurred at a defined percentage, inertialsensors indicate that the vehicle is parked on an incline, indicated byplot 520. Between time t₁ and t₂ it may be determined whether thevehicle parking condition may result in fuel system isolation, or theformation of isolated vapor dome(s). For example, as described above,inertial sensors may indicate vehicle pitch and bank (compound angle),or vehicle grade. In the example timeline 500, for illustrationpurposes, it is assumed that the vehicle is parked on a hill whereinvehicle bank is negligible and thus not included in the discussion.However, in some examples vehicle bank may be significant. Upondetermining the vehicle grade (compound angle), a fuel level may bedetermined, and as described above, a 2D lookup table may be stored inthe vehicle control system memory wherein an indicated vehicle compoundangle, may be compared to an indicated fuel level, and if the fuel leveland vehicle compound angle (e.g., vehicle grade) is equal to or greaterthan a predetermined threshold, it may be indicated that the fuel systemmay be restricted from the emissions control system, and/or isolatedfuel tank vapor dome(s) may result. As the fuel level is quite high,indicated by plot 510, between time t₁ and t₂ it may be determined thatthe fuel system may be isolated from the emission control system.Accordingly, between time t₁ and t₂ it may be determined the amount ofvehicle leveling that may be required in order to mitigate the isolationof the fuel system from the emission control system, and/or to mitigatethe formation of fuel tank vapor dome(s). As described above, thedetermination may be similarly based on the signals acquired frominertial sensors, the indicated fuel level in the fuel tank, andcomputer aided design (CAD) modeling of the particular fuel tankinstalled in vehicle, and may be retrievable via a 2D vehicle lookuptable. As indicated, line 525 represents a first threshold vehicle grade(compound angle) for which fuel system isolation, and/or the formationof isolated fuel tank vapor dome(s) are no longer indicated. Followingthe determination of the amount of leveling required, it may further bedetermined whether the amount of corrective leveling is greater than amaximum amount of leveling possible by the vehicle's active suspensionsystem. In this example timeline 500, the amount of corrective levelingis assumed to not exceed the maximum amount of leveling possible. Assuch, between time t₂ and t₃ the vehicle's active suspension system isemployed in order to level the vehicle the determined amount, asindicated by plot 520.

As the corrective leveling of the vehicle via the vehicle's activesuspension system may cause fuel sloshing in the fuel tank, subsequentto the leveling of the vehicle the determined amount, the vehicle systemmay be allowed to stabilize for a predetermined period of time prior toexecution of an evaporative emissions test. As such, between time t₃ andt₄ the CVV, indicated by plot 535, is maintained open to allow fuelsystem stabilization.

At time t₄ the CVV may be commanded closed. As such, the fuel system andemissions control system may be isolated from atmosphere. Accordingly,pressure may build in the fuel system and emissions control system,indicated by plot 540, and as measured by the FTPT. Between time t₄ andt₅ pressure in the fuel system and emissions control system builds, butdoes not reach a threshold pressure build, indicated by line 545.Instead, the pressure build is observed to plateau. As such, the fuelsystem and emission control system did not pass the evaporativeemissions test on a pressure build, but may instead pass on a vacuumbuild, as described below. Thus, at time t₅ the CVV is commanded open,and between time t₅ and t₆ pressure in the fuel system and emissionscontrol system returns to atmospheric pressure.

At time t₆ the CVV is commanded closed, and pressure in the fuel systemand emissions control system is monitored for a duration of time. As thefuel tank cools, vacuum is observed to develop in the fuel tank, and attime t₇ the vacuum build reaches a threshold vacuum level, representedby line 550. As such, the fuel system and emission control system may beindicated to pass the evaporative emissions test, and thus undesiredemissions are not indicated, as indicated by plot 555.

As the evaporative emissions test procedure is complete at time t₇, CVVmay be commanded open. Accordingly, between time t₇ and t₈ pressure inthe fuel system and emissions control system return to atmosphericpressure. Further, between time t₇ and t₈ the vehicle's activesuspension system may be employed in order to return the vehicle to thedefault state, or in other words to return the vehicle to thepre-leveling conditions, as indicated by plot 520.

At time t₈ a vehicle-on event is detected. Between time t₈ and t₉ thevehicle is observed to travel down a hill, indicated by plot 515,wherein the vehicle grade (compound angle) may be indicated by inertialsensors, as illustrated by plot 520. At time t₉ the vehicle beginstravelling along a flat surface, and between time t₉ and t₁₀ no changesin road grade, and thus no changes in vehicle grade, are indicated. Attime t₁₀ the vehicle is observed to being travel up a hill. Between timet₁₀ and t₁₁ travel up the hill is indicated, until the vehicle isobserved to park on the hill at time t₁₁, indicated by the detection ofa vehicle-off event at time t₁₁.

Between time t₁₁ and t₁₂ it may be determined whether the vehicleparking condition may result in fuel system isolation, or the formationof isolated vapor dome(s). For example, inertial sensors may indicatevehicle grade (compound angle). As described above, in the exampletimeline 500, it is assumed that the vehicle is parked on a hill whereinvehicle bank is negligible and thus not included in the discussion.However, in some examples vehicle bank may be significant. Upondetermining the vehicle compound angle (e.g., vehicle grade), a fuellevel may be determined, and as described above, a 2D lookup table maybe utilized to determine whether the fuel system may be restricted fromthe emissions control system, and/or whether isolated fuel tank vapordome(s) may be indicated. As the fuel level is still near half full, andthe vehicle is parked on a steep hill, between time t₁₁ and t₁₂ it maybe determined that the fuel system may be isolated from the emissioncontrol system. Accordingly, between time t₁₁ and t₁₂ the amount ofleveling required to mitigate the isolation of the fuel system from theemission control system may be determined, as described above. Asindicated, line 530 represents a second threshold vehicle grade forwhich fuel system isolation, and/or the formation of isolated fuel tankvapor dome(s) are no longer indicated. As described above, following thedetermination of the amount of leveling required, it may further bedetermined whether the amount of corrective leveling exceeds a maximumamount of leveling possible by the vehicle's active suspension system.In this example timeline 500, the amount of corrective levelingindicated between time t₁₁ and t₁₂ is assumed to exceed the maximumamount of leveling capable by employing the vehicle's active suspensionsystem. As such, between time t₁₂ and t₁₃ the CVV is maintained open,and no corrective leveling action is undertaken, indicated by plot 520.As an evaporative emissions test procedure was not undertaken during thevehicle-off event commencing at time t₁₁, a flag may be set in thecontroller to retry an evaporative emissions test at the nextvehicle-off event.

In this way, the entire fuel system and emissions control system may bediagnosed for potential undesired emissions, even under circumstanceswherein vehicle parking conditions may otherwise result in isolation ofthe fuel system from the emissions control system and/or result in theformation of isolate fuel tank vapor dome(s). As such, opportunities forconducting evaporative emissions tests may be advantageously increased,and potential violations of regulatory requirements for evaporativeemissions testing may be reduced. Accordingly, release of undesiredemissions to the atmosphere may be reduced.

The technical effect of conducting evaporative emissions testingprocedures subsequent to leveling the vehicle under certain parkingconditions is to indicate a vehicle pitch angle and bank angle, and inconjunction with an indicated level of fuel in the fuel tank, indicate adetermined amount of corrective leveling required to mitigate fuelsystem isolation or the formation of isolated fuel tank vapor dome(s).By CAD modeling of the fuel tank, a lookup table may be utilized suchthat the vehicle may be leveled a determined amount, thus mitigatingfuel system isolation issues. In this way, the amount of leveling may beminimized such that the fuel system isolation issues are mitigatedwithout excessive or unwarranted leveling.

The systems described herein and with reference to FIGS. 1-3, along withthe methods described herein and with reference to FIG. 4 may enable oneor more systems and one or more methods. In one example, a methodcomprises, responsive to a first vehicle-off condition, maintaining avehicle compound angle with respect to ground and conducting anevaporative emissions test; and responsive to a second vehicle-offcondition, leveling a vehicle a determined amount and then conductingthe evaporative emissions test. In a first example of the method, themethod includes wherein maintaining the vehicle compound angle withrespect to ground is based on the vehicle compound angle and a fuellevel in a fuel tank below a predetermined threshold; and whereinleveling the vehicle a determined amount is based on the vehiclecompound angle and the fuel level above a predetermined threshold. Asecond example of the method optionally includes the first example andfurther includes wherein the predetermined threshold is retrieved via a2D lookup table comprising the vehicle compound angle and the fuellevel. A third example of the method optionally includes one or more oreach of the first and second examples and further includes wherein thefirst vehicle-off condition comprises the vehicle compound angle and thefuel level below the predetermined threshold such that one or more of afuel tank valve(s) is maintained open, and where no section of the fueltank is isolated from any other section of the fuel tank; and whereinthe second vehicle-off condition comprises the vehicle compound angleand the fuel level above the predetermined threshold such that one ormore of the fuel tank valve(s) are closed, and/or one or more sectionsof the fuel tank are isolated from another section of the fuel tank. Afourth example of the method optionally includes any one or more or eachof the first through third examples and further includes whereinleveling the vehicle a determined amount includes calculating thedetermined amount based on the vehicle compound angle and the fuellevel, and leveling the vehicle until the one or more fuel tank valve(s)are open and/or where no section of the fuel tank is isolated fromanother section of the fuel tank; and wherein the leveling is notexecuted if it is indicated that the determined leveling amount isgreater than a predetermined threshold. A fifth example of the methodoptionally includes any one or more or each of the first through fourthexamples and further includes wherein leveling the vehicle a determinedamount includes leveling the vehicle via an onboard active suspension. Asixth example of the method optionally includes any one or more or eachof the first through fifth examples and further includes wherein theleveling of the vehicle a determined amount is maintained for theduration of the evaporative emissions test and wherein the vehicle isreturned to default conditions subsequent to completion of theevaporative emissions test. A seventh example of the method optionallyincludes any one or more or each of the first through sixth examples andfurther includes wherein the first condition includes commencing theevaporative emissions test subsequent to an indication that the vehicleis not occupied; and wherein the second condition includes commencingleveling the vehicle and conducting the evaporative emissions testsubsequent to the indication that the vehicle is not occupied. An eighthexample of the method optionally includes any one or more or each of thefirst through seventh examples and further includes wherein theindication that the vehicle is not occupied includes one or more of apowertrain control module query of seat load cells, door sensingtechnology, and onboard cameras. A ninth example of the methodoptionally includes any one or more or each of the first through eighthexamples and further includes wherein the first condition includesaborting the evaporative emissions test responsive to an indication thatthe vehicle has become occupied during the evaporative emissions test;wherein the second condition includes aborting the evaporative emissionstest and returning the vehicle to default conditions responsive to anindication that the vehicle has become occupied during the evaporativeemissions test; and wherein the indication that the vehicle has becomeoccupied during the evaporative emissions test includes one or more of apowertrain control module query of seat load cells, door sensingtechnology, and onboard cameras.

Another example of a method comprises responsive to a vehicle-offcondition, indicating a fuel level in a fuel tank; indicating a vehiclecompound angle via on-board sensors; and responsive to the fuel leveland the vehicle compound angle above a predetermined threshold; levelingthe vehicle a determined amount via the employment of an on-board activesuspension; conducting an evaporative emissions test; and subsequent tocompletion of the evaporative emissions test, returning the vehicle todefault conditions. In a first example of the method, the methodincludes wherein the predetermined threshold is based on computer aideddesign modeling of the fuel tank, and wherein the predeterminedthreshold is retrieved via a 2D lookup table comprising the vehiclecompound angle and the fuel level. A second example of the methodoptionally includes the first example and further includes whereinresponsive to the fuel level and vehicle compound angle below thepredetermined threshold, conducting the evaporative emissions testwithout leveling of the vehicle. A third example of the methodoptionally includes any one or more of the first and second examples andfurther includes wherein the fuel level and vehicle compound angle abovethe predetermined threshold includes one or more of a fuel tank valve(s)being closed, and/or one or more sections of the fuel tank isolated fromother sections of the fuel tank; and wherein the fuel level and vehiclecompound angle below the predetermined threshold includes one or more ofthe fuel tank valve(s) maintained open, and/or where no section of thefuel tank is isolated from any other section of the fuel tank. A fourthexample of the method optionally includes any one or more of the firstthrough third examples and further includes wherein conducting theevaporative emissions test without leveling of the vehicle commencessubsequent to an indication that the vehicle is not occupied; whereinleveling the vehicle the determined amount via the employment of anon-board active suspension and conducting the evaporative emissions testcommences subsequent to the indication that the vehicle is not occupied;and wherein the indication that the vehicle is not occupied includes oneor more of a powertrain control module query of seat load cells, doorsensing technology, and onboard cameras. A fifth example of the methodoptionally includes any one or more or each of the first through fourthexamples and further comprises aborting the evaporative emissions testbeing conducted without leveling of the vehicle upon indication that thevehicle has become occupied during the course of the evaporativeemissions test; aborting the evaporative emissions test being conductedvia leveling of the vehicle and returning the vehicle to defaultconditions upon indication that the vehicle has become occupied duringthe course of the evaporative emissions test; wherein the indicatingincludes the one or more of the powertrain control module query of seatload cells, door sensing technology, and onboard cameras.

An example of a system for a vehicle comprises a fuel system coupled toan evaporative emissions control system, the fuel system and evaporativeemissions control system isolatable from atmosphere via one or morevalves; a fuel tank housed within the fuel system, the fuel tankcomprising one or more fuel tank vent valves; an active suspensionsystem; a plurality of on-board inertial sensors; one or more of a seatload cell(s), a door sensing technology, and an onboard camera(s); acontroller configured with instructions stored in non-transitory memory,that when executed, cause the controller to: responsive to a vehicle-offevent; indicate a fuel level in the fuel tank; indicate a vehiclecompound angle via the plurality of on-board inertial sensors; indicatea vehicle-occupancy via the one or more of the seat load cells, the doorsensing technology, and the onboard camera(s); and responsive to thefuel level and vehicle compound angle above a predetermined thresholdand an indication that the vehicle is not occupied; level the vehicle adetermined amount via employing the active suspension system; isolatethe fuel system and evaporative emissions control system; conduct anevaporative emissions test procedure; and subsequent to the completionof the evaporative emissions test procedure; return the vehicle to adefault state via employing the active suspension system. In a firstexample, the system further includes wherein the predetermined thresholdis based on the fuel level and the vehicle compound angle where one ormore of a fuel tank valve(s) is closed and/or one or more sections ofthe fuel tank are isolated from other sections of the fuel tank, andwhere the controller is configured with instructions stored innon-transitory memory, that when executed, cause the controller to:calculate the determined amount of leveling wherein subsequent toleveling the vehicle the determined amount, the fuel level and vehiclecompound angle is below the predetermined threshold where the one ormore fuel tank valve(s) are open and/or no section(s) of the fuel tankare isolated from other section(s) of the fuel tank. A second example ofthe system optionally include the first example and further includeswherein the controller is configured with instructions stored innon-transitory memory, that when executed, cause the controller to:responsive to the fuel level and vehicle compound angle below apredetermined threshold and the indication that the vehicle is notoccupied; execute the evaporative emissions test procedure withoutleveling of the vehicle; and responsive to an indication that thevehicle has become occupied during the course of the evaporativeemissions test, in a first condition, abort the evaporative emissionstest responsive to the test being conducted without leveling of thevehicle; and in a second condition, abort the evaporative emissions testresponsive to the test being conducted via leveling of the vehicle andreturning the vehicle to default conditions. A third example of thesystem optionally includes any one or more or each of the first andsecond examples and further includes wherein the controller isconfigured with instructions stored in non-transitory memory, that whenexecuted, cause the controller to: responsive to the fuel level andvehicle compound angle above a predetermined threshold; indicate thedetermined leveling amount; indicate a maximum leveling capacity of thevehicle; and responsive to the determined leveling amount greater thanthe maximum leveling capacity; do not conduct leveling and do notconduct the evaporative emissions test procedure.

Note that the example control and estimation routines included hereincan be used with various engine and/or vehicle system configurations.The control methods and routines disclosed herein may be stored asexecutable instructions in non-transitory memory and may be carried outby the control system including the controller in combination with thevarious sensors, actuators, and other engine hardware. The specificroutines described herein may represent one or more of any number ofprocessing strategies such as event-driven, interrupt-driven,multi-tasking, multi-threading, and the like. As such, various actions,operations, and/or functions illustrated may be performed in thesequence illustrated, in parallel, or in some cases omitted. Likewise,the order of processing is not necessarily required to achieve thefeatures and advantages of the example embodiments described herein, butis provided for ease of illustration and description. One or more of theillustrated actions, operations and/or functions may be repeatedlyperformed depending on the particular strategy being used. Further, thedescribed actions, operations and/or functions may graphically representcode to be programmed into non-transitory memory of the computerreadable storage medium in the engine control system, where thedescribed actions are carried out by executing the instructions in asystem including the various engine hardware components in combinationwith the electronic controller.

It will be appreciated that the configurations and routines disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-12, opposed 4, and other engine types. The subject matter ofthe present disclosure includes all novel and non-obvious combinationsand sub-combinations of the various systems and configurations, andother features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

1. A method comprising: responsive to a first vehicle-off condition, maintaining a vehicle compound angle with respect to ground and conducting an evaporative emissions test; and responsive to a second vehicle-off condition, leveling a vehicle a determined amount and then conducting the evaporative emissions test.
 2. The method of claim 1, wherein maintaining the vehicle compound angle with respect to ground is based on the vehicle compound angle and a fuel level in a fuel tank below a predetermined threshold; and wherein leveling the vehicle a determined amount is based on the vehicle compound angle and the fuel level above the predetermined threshold.
 3. The method of claim 2, wherein the predetermined threshold is retrieved via a 2D lookup table comprising the vehicle compound angle and the fuel level.
 4. The method of claim 2, wherein the first vehicle-off condition comprises the vehicle compound angle and the fuel level below the predetermined threshold such that one or more of a fuel tank valve(s) is maintained open, and where no section of the fuel tank is isolated from any other section of the fuel tank; and wherein the second vehicle-off condition comprises the vehicle compound angle and the fuel level above the predetermined threshold such that one or more of the fuel tank valve(s) are closed, and/or one or more sections of the fuel tank are isolated from another section of the fuel tank.
 5. The method of claim 2, wherein leveling the vehicle a determined amount includes calculating the determined amount based on the vehicle compound angle and the fuel level, and leveling the vehicle until one or more fuel tank valve(s) are open and/or where no section of the fuel tank is isolated from another section of the fuel tank; and wherein the leveling is not executed if it is indicated that the determined leveling amount is greater than a predetermined threshold.
 6. The method of claim 1, wherein leveling the vehicle a determined amount includes leveling the vehicle via an onboard active suspension.
 7. The method of claim 1, wherein the leveling of the vehicle a determined amount is maintained for a duration of the evaporative emissions test and wherein the vehicle is returned to default conditions subsequent to completion of the evaporative emissions test.
 8. The method of claim 1, wherein the first condition includes commencing the evaporative emissions test subsequent to an indication that the vehicle is not occupied; and wherein the second condition includes commencing leveling the vehicle and conducting the evaporative emissions test subsequent to the indication that the vehicle is not occupied.
 9. The method of claim 8, wherein the indication that the vehicle is not occupied includes one or more of a powertrain control module query of seat load cells, door sensing technology, and onboard cameras.
 10. The method of claim 1, wherein the first condition includes aborting the evaporative emissions test responsive to an indication that the vehicle has become occupied during the evaporative emissions test; wherein the second condition includes aborting the evaporative emissions test and returning the vehicle to default conditions responsive to the indication that the vehicle has become occupied during the evaporative emissions test; and wherein the indication that the vehicle has become occupied during the evaporative emissions test includes one or more of a powertrain control module query of seat load cells, door sensing technology, and onboard cameras. 11-20. (canceled) 